CPU-Temperature as a graph with RRDtool

thgmirror · May 25, 2022, 7:40 PM

I added a graph about the progress of the CPU-temperture of my RPI3 to my MM via RRDtool:

It looks a little bit nerdy, but the temperature is a nerdy hardware characteristic. OK, it is not so beautiful like grafana…but much easier to use.
Therefor, it needs only a few steps to realize it:

sudo apt-get install rrdtool

will install it.
Only one time create the database in the terminal session:

rrdtool create cputemp.rrd --step 300 DS:temp:GAUGE:600:-20:90 RRA:AVERAGE:0.5:12:24 RRA:AVERAGE:0.5:288:31

Add two tasks to crontab:

2-57/5 * * * * rrdtool update cputemp.rrd N:$(vcgencmd measure_temp | cut -c "6-9")

moves every 5 minutes the temperature to the database established above.

0 * * * * rrdtool graph /home/pi/MagicMirror/modules/cputemp.gif --start -24h --title "CPU-Temperatur" --vertical-label "Grad Celsius" --disable-rrdtool-tag DEF:cputemperatur=cputemp.rrd:temp:AVERAGE LINE1:cputemperatur#ff0000:"CPU-Temperatur" ;

generates once in an hour a graph which will be displayed later. If you like, you can adjust the map legend (“CPU-Temperatur” and “Grad Celsius”) with descriptions in your language.

Now create a file named cputemp.html in the modules-folder of your MM:

<HTML>
<HEAD>
<TITLE>CPU Temperatur</TITLE>
</HEAD>
<body bgcolor=#000000>
	<img src="cputemp.gif"/>
</body>
</HTML>

and use MMM-SmartWebDisplay in your config.js to show it:

//#################################################################################
		{
			disabled: false,
			module: 'MMM-SmartWebDisplay',
			position: 'top_center',
			config: {
				logDebug: false,
				height: "180",
				width:"500",
				updateInterval: 0,
				NextURLInterval: 0,
				displayLastUpdate: false,
				url: ["/modules/cputemp.html"],
				}
		},
//#################################################################################

Based on these steps, some more modifications of the appearance are possible. Please use your favorite search-engine for more.